Actually don't have as much time as I wish I had, just a lot of pre-planning. The ranking logos I did last year as mentioned above and the only thing I added this year was the Klingon logo, stars background, and modified the CSS. All in all took me a few hours, but started it at the beginning of March in anticipation of April 1st.
In fact if you were using the upcoming forum template you may have seen this change as early as a week ago. Was thinking that someone was for sure going to mention the change on the forums because they were using that theme but guess everyone who is using that isn't an active member.